Rice is the staple food crop for a large part of the human population in the world today. A crop failure, for any reason, poses a real threat of starvation. Rice blast, caused by a fungus (Magnaporthe oryzae; anamorph: Pyricularia oryzae) is by far the most important disease of the many diseases that attack rice. The fungus causes lesions to form on leaves, stems, peduncles, panicles, seeds, and even roots. So great is the potential threat for crop failure from this disease that it has been ranked among the most important plant diseases of them all. The rice blast fungus is found wherever rice is grown and is a major threat. Each year it is estimated to destroy enough rice to feed more than 60 million people. Failures of entire rice crops have resulted directly from rice blast epidemics. There is a need for more effective agents for protecting plants, including rice, from damage caused by this pathogen.
Fungicides are compounds, of natural or synthetic origin, which act to protect plants against damage caused by fungi. Current methods of agriculture rely heavily on the use of fungicides. In fact, some crops cannot be grown usefully without the use of fungicides. The use of fungicides allows a grower to increase the yield and the quality of the crop and consequently, increase the value of the crop. In most situations, the increase in value of the crop is worth at least three times the cost of the use of the fungicide.
Unfortunately, no one fungicide is useful in all situations and repeated usage of a single fungicide frequently leads to the development of resistance to that and related fungicides. Consequently, research is being conducted to produce fungicides and combinations of fungicides that are safer, that have better performance, that require lower dosages, that are easier to use, and that cost less. Combinations are also being studied that produce synergism, i.e., the activity of two, or more, compounds exceeds the activities of the compounds when used alone.
It is an object of this invention to provide synergistic compositions comprising fungicidal compounds. It is a further object of this invention to provide processes that use these synergistic compositions.
In one embodiment the invention pertains to a synergistic fungicidal mixture comprising a fungicidally effective amount of a compound of Formula I and at least one fungicide selected from the group consisting of tricyclazole, azoxystrobin, carpropamid, probenazole, kasugamycin, and boscalid

Advantageously, the synergistic compositions comprising tricyclazole, probenazole, carpropamid, and/or kasugamycin with Formula I are capable of preventing or curing, or both, rice disease caused by, for example, Magnaporthe oryzae. Similarly, the synergistic compositions comprising azoxystrobin and/or boscalid with Formula I are capable of preventing or curing, or both, rice disease caused by a wide range of fungi including, for example, Basidiiomycetes and/or Ascomycetes. In accordance with this invention, synergistic compositions are provided along with methods for their use.